Research On Key Technologies Of Blockchain Based Spectrum Sharing

Blockchain is a decentralized ledger or database combined with distributed peer to peer network,data encryption and consensus algorithm.Blockchain provides users with trust through technical means,enabling them to complete transactions without mutual trust basis.Moreover,its decentralized storage mode and consensus mechanism make the transaction records cannot be tampered with.Blockchain was originally created in bitcoin as the underlying architecture for service transactions,and has since expanded into a wide variety of digital currencies and even financial services.Subsequently,the consortium blockchain,with some changes to the architecture and consensus mechanisms,is thought to be able to move beyond finance to commercial areas such as digital asset authentication and supply chain traceability.Nowadays,as our country attaches more importance to blockchain,people are exploring the possibility of combining various fields with blockchain,but more improvements need to be made in specific implementation.Considering of the advantages of blockchain,this thesis researches spectrum sharing technology based on blockchain,and provides pricing scheme for participants with game theory in spectrum sharing.This thesis proposes an improved Optimized Scalable Byzantine Fault Tolerance algorithm suitable for spectrum sharing based on the PBFT(Practical Byzantine Fault Tolerance)algorithm.Finally we build a private chain based on Ethereum and implement several functions such as ether transaction and mining.The main work in this thesis is as follows:(1)To solve the problem of insufficient utilization and serious waste of spectrum resources,we build a spectrum sharing system based on consortium blockchain,so that operators or other spectrum owners can rent or lease spectrum safely.Transactions will be verified by consensus nodes.Illegal transactions will not be recognized and called back and legal transaction data will be stored in the local blockchain of each node after transaction completed.We use game theory to establish the utility function for the operators of the trading spectrum and makes the operators of the leased spectrum get the optimal rental price.Finally we simulates the game model and results show that this method can effectively improve the spectrum utilization.(2)The PBFT algorithm is generally chosen as the consensus algorithm in the case of byzantine errors,but some problems inherent in the algorithm make it unsuitable for direct usage in spectrum sharing scenario.Therefore,we propose an improved consensus algorithm called OSBFT(Optimized Scalable Byzantine Fault Tolerance).The improved algorithm reduces consensus steps,adds data synchronization,and enables nodes to join and exit consensus freely.Simulation results show that the improved algorithm can effectively reduce the consensus delay and computational resource consumption.(3)This thesis builds a private blockchain based on Ethereum.We also build user accounts and obtain ether through mining.Users can view the balance of an account and send ether from one account to another.In addition,we also use the Ethereum wallet client to complete the same functions with the private chain built,and make a brief introduction of the smart contract function of the wallet client.